Investigation of reactive acrylic monomers for their effect on the temperature range and operating voltage of polymer-stabilised optically isotropic liquid crystal blue phases

Synthesis of various reactive acrylic monomers (RMs) to be used as components in liquid crystalline blue phase (LCBP) mixtures has been carried out in order to investigate their effect on temperature range and operating voltage. All the newly synthesised RMs were fully purified and characterised. These were added in various molar ratios to LCBP mixtures, which were stabilised by ultraviolet polymerisation, and improvements in the operating voltage and temperature range were studied. The compatibility of LCBP and monomer side-chains was investigated in terms of polarity and alkyl chain length.     

Alkaline steeping of dissolving pulp. Part II: Soluble compounds in the press lye

This work describes the comprehensive characterization of the degradation products obtained after the alkaline steeping of dissolving pulp. Total chlorine free bleached beech sulfite pulp was treated with 18 % sodium hydroxide at different temperatures (40, 50 and 60 °C) for time periods of up to 80 h. After the removal of the insoluble cellulose, the remaining alkali solution was treated with sulfuric acid to precipitate the β-fraction. With extended treatment times and temperatures, the proportion of xylan in the β-fraction is increased. However, the molar mass distribution and the amount of 4-O-methylglucuronic acid in the β-fraction revealed no clear trend as a function of the treatment conditions. In total 13 hydroxy acids were identified in the acid soluble γ-fraction, of which glucoisosaccharinic, glycolic, lactic and xyloisosaccharininc acids were among the most abundant hydroxy acids representing the degradation products from C6- and C5-sugars.     

L1 -stability of the solutions to an integral evolution equation of the non-linear particle transport theory

Summary The problem of L ¹-stability of the solutions to a non linear integral equation arising in particles transport theory is studied. This equation can represent the standard spatially homogeneous Boltzmann equation in the case of Maxwellium particles with cut off.

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Sommario Si studia la stabilita non lineare nella norma di L ¹ delle soluzioni di un'equazione integrale non lineare della teoria del trasporto di particelle, cui si riduce l'usuale equazione di Boltzmann nel caso spazialmente omogeneo e per particelle Maxwelliane con cut-off.

     

Asymptotics of the Fast Diffusion Equation via Entropy Estimates

We consider non-negative solutions of the fast diffusion equation u _t  = Δ u ^m with m ∈ (0, 1) in the Euclidean space , d ≧ 3, and study the asymptotic behavior of a natural class of solutions in the limit corresponding to t → ∞ for m ≧ m _c  = (d − 2)/d, or as t approaches the extinction time when m < m _c . For a class of initial data, we prove that the solution converges with a polynomial rate to a self-similar solution, for t large enough if m ≧ m _c , or close enough to the extinction time if m < m _c . Such results are new in the range m ≦ m _c where previous approaches fail. In the range m _c  < m < 1, we improve on known results.     

Comparison results for oscillation of nonlinear differential equations

((without abstract.))     

Recent developments in the synthesis of heterocyclic derivatives by PdI2-catalyzed oxidative carbonylation reactions

A simple catalytic system, consisting of PdI₂ in conjunction with an excess of KI, has proven to be very valuable for the direct one-step synthesis of a variety of heterocyclic derivatives by oxidative carbonylation of suitably functionalized alkynes. The same catalyst also promoted the oxidative carbonylation of β-amino alcohols to oxazolidin-2-ones with unprecedented catalytic efficiencies for this kind of reaction.     

Biogas production fromJatropha curcas press-cake

Applied Biochemistry and Biotechnology - Seeds of the tropical plantJatropha curcas (purge nut, physic nut) are used for the production of oil. Several methods for oil extraction have been...     

Asymptotic behaviour of solutions for second order nonlinear autonomous differential equations

For a class of second order nonlinear autonomous differential equations asymptotic properties of the solutions as are studied. The investigation is done in the phase plane and the phase portrait of the equivalent system is obtained by using the zero-isocline function. Some suffcient conditions are presented which for the case of Liénard equation become also necessary. Received December 21, 1995